The Abyss, also known as the Infinite Dungeon, is a dungeon located in the volcano next to Saint Wesburn in Wesburn. The dungeon is infinitely deep and there is a waypoint at every 10th floor so that you can return to that spot in the future. These waypoints continue up to and including level 210; thereafter you continue to climb without the aid of the waypoint.
Reward for reaching every 10th floor is an extra monster slot.
Unlike in normal dungeons where chests typically give silver, chests will always give a gem with a high bonus in the Abyss. These chests are quite rare, though!
Many types of both strong and weak monsters appear in the Abyss. Some of the best monsters in the game can be found in here. Note, though, that you cannot catch any monster in this dungeon; capture cards won't work.
Here are the monsters that appear in the Abyss:
Go to the Top 20 List Tips: When going inside the dungeon (abyss) the best monster to use is iron king and two morfeus so you can use sleep and dream hunt this will instantly kill all the monster at the frontline.